6-methyl-1,2,3-oxathiazin-4(3H)-one 2,2-dioxide, potassium salt

Repeated dose toxicity: oral

Administrative data

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1974

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Scientifically reliable study with sufficient information for evaluation and assessment

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1974

Report date:

1974

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)

Deviations:

yes

Remarks:

fewer parameters in clinical pathology, gross pathology, histopathology, no ophthalmology

GLP compliance:

no

Remarks:

Study performed prior to implementation of GLP

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

6-methyl-1,2,3-oxathiazine-4(3-H)-one-2,2-dioxide potassium salt

IUPAC Name:

6-methyl-1,2,3-oxathiazine-4(3-H)-one-2,2-dioxide potassium salt

Constituent 2

Reference substance name:

6-methyl-1,2,3-oxathiazin-4(3H)-one 2,2-dioxide, potassium salt

EC Number:

259-715-3

EC Name:

6-methyl-1,2,3-oxathiazin-4(3H)-one 2,2-dioxide, potassium salt

Cas Number:

55589-62-3

Molecular formula:

C4H5NO4S.K

IUPAC Name:

potassium 6-methyl-2,2,4-trioxo-3,4-dihydro-1,2λ⁶,3-oxathiazin-3-ide

Constituent 3

Reference substance name:

Acesulfame potassium

IUPAC Name:

Acesulfame potassium

Test material form:

solid: crystalline

Details on test material:

- Name of test material (as cited in study report): Hoe 0-95 K
- Physical state: crystalline powder
- Analytical purity:>99.8%
- Lot/batch No.: VP 528 G 511
- Stability under test conditions: stable
- Storage condition of test material: room temperature

Test animals

Species:

rat

Strain:

other: Wistar derived

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: CIVO colony, The Netherlands
- Age at study initiation: young adult
- Housing: five per cage, scren-bottomed cages
- Diet: ad libitum (prepared laborytory diet)
- Water: ad libitum (tap water)

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 24 - 26

Administration / exposure

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

DIET PREPARATION
- Rate of preparation of diet (frequency): each fourth day
- Mixing appropriate amounts with (Type of food): prepared laboratory diet
- Storage temperature of food: room temperature

Analytical verification of doses or concentrations:

not specified

Details on analytical verification of doses or concentrations:

Not applicable

Duration of treatment / exposure:

90 days

Frequency of treatment:

daily

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 other: %

Remarks:

(0 ppm or 0 mg/kg bw)

Doses / concentrations 2

Dose / conc.:

1 other: %

Remarks:

(10000 ppm or 500 mg/kg bw)

Doses / concentrations 3

Dose / conc.:

3 other: %

Remarks:

(30000 ppm or 1500 mg/kg bw)

Doses / concentrations 4

Dose / conc.:

10 other: %

Remarks:

(100000 ppm or 5000 mg/kg bw)

No. of animals per sex per dose:

10

Control animals:

yes, plain diet

Details on study design:

- Dose selection rationale: Request of sponsor
- Rationale for animal assignment (if not random): Forty male and forty female weanling albino rats from the CIVO-colony (Wistar derived) were divided according to body weight into four groups of ten males and ten females each

Positive control:

None

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes, in first 4 weeks and in weeks 11 and 12
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No
- Time schedule for examinations:

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: prior to termination in week 13
- Anaesthetic used for blood collection: No
- Animals fasted: No
- How many animals: 10 per sex and group
- Parameters examined: haemoglobin content, haematocrit value, red blood cell counts and total and differentialwhite blood cell counts

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: prior to termination in week 13
- Animals fasted: No
- How many animals: 10 per sex and group
- Parameters examined: serum glutamic-pyruvic transaminase (SGPT), serum glutamic-.oxalacetic transaminase (SGOT), serum alkalinephosphatase (SAP) activity and total serum protein and albumin content

URINALYSIS: Yes
- Time schedule for collection of urine: prior to termination in week 13
- Metabolism cages used for collection of urine: No data
- Animals fasted: Yes
- Parameters examined: appearance, pH, glucose, protein, occult blood, ketones and microscopy of the sediment

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes (complee)
Organ weights: heart, kidneys, liver, spleen, brain, testicles/ovaries, thymus, thyroid, adrenals and caecum (filled and empty)

HISTOPATHOLOGY: Yes
In all male and female rats of control and high dose groups
Organs/tissues: lung, salivary glands, trachea, thoracic aorta, skeletal muscle, axillary and mesenteric lymph nodes, pancreas, urinary bladder, prostate, epididymis, uterus, mammary gland, esophagus, fore- and glandular stomach, duodenum, ileum and colon

Statistics:

Mean and standard deviation was calculated, significance levels: * p<0.05, **p<0.01, ***p<0.001

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

General behaviour was not adversely affected at any dietary level. Slight diarrhoea was observed in males of the highest dose group.

Mortality:

mortality observed, treatment-related

Description (incidence):

No mortality occurred.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Body weight and body weight gain was slightly reduced during the first 3 - 4 weeks of treatment in the animals of both sexes.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

The food consumption in the 10% group was slightly reduce during the first two to three weeks and slightly increased thereafter.

Food efficiency:

effects observed, treatment-related

Description (incidence and severity):

Food efficiency in the 10% group was distinctly lower than in controls during the first two to three weeks and slightly increased once the food consumption of the three groups was corrected for the intake of the test substance and expressed as the actual intake of stock diet only, the corrected food efficiency was similar in all groups, except for a relatively low in males of the 10% group.

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

A slight increase in haemoglobin concentration was observed in males of the high dose group

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

Serum enzyme activities and albumin levels were comparable in all groups. Total serum protein level was slightly decreased in females of the high dose group.

Urinalysis findings:

no effects observed

Description (incidence and severity):

Urine analyses were essentially normal in all groups.

Behaviour (functional findings):

not examined

Immunological findings:

not specified

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

The relative weights of the caecum were distinctly increased at the high dose group in both sexes and at the mid dose group in females only. The weights of the liver and kidneys were slightly increased in females of the high dose group.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Gross examination identified enlarged caeca in the 10% group in females and males without morphological differences betwee test and control rats.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not examined

Effect levels

Key result

Dose descriptor:

NOAEL

Effect level:

>= 30 000 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

organ weights and organ / body weight ratios

Remarks on result:

other: Increased of the relative weights of the caecum but microscopic axamination did not reveal any abnormalities that couold be attribuited to the test substance.

Target system / organ toxicity

Critical effects observed:

no

Applicant's summary and conclusion

Conclusions:

No Observed Adverse Effects Level (NOAEL) for subchronic (90 days) oral toxicity in male and female Wistar rats was 30000 ppm (corresponding to about 1500 mg/kg bw/day) under the conditions of the study. Even the highest dose level of 100000 ppm (corresponding to about 3000 mg/kg bw/day) resulted in no severe signs of toxicity. This dose level clearly exceeded the current limit dose level of 1000 mg/kg bw/day.

Executive summary:

The subchronic oral toxicity of Acesulfame potassium was investigated in male and female Wistar rats. Each 10 males and 10 females received dose levels of 0, 1%, 35 and 10% in the diet (0, 10000, 30000 100000 ppm, corresponding to about 0, 300, 1500, 3000 mg/kg bw/day) daily during a period of 90 days. Mortality, clinical findings and behavior were examined at least once a day, while body weight, food consumption were determined at regulary intervals. At the end of the application, hematology, clinical chemistry and urinalysis were performed. After sacrifice, a complete necropsy was performed, organ weights were determined and the animals of the control and high dose groups were subjected to histopathology.

 

This study is assessed as appropriate and valid since it was performed comparable to an internationally accepted testing guideline with only minor deviations. Reporting, assessment and data presentation in the study report was considered as appropriate.

 

Body weight and body weight gain was slightly reduced during the first 3 - 4 weeks of treatment in the animals of both sexes. Food consumption/food efficiency of the highest dose was slightly reduced during the first two to three weeks and slightly increased thereafter. A slight increase in haemoglobin concentration was observed in males of the high dose group. Serum enzyme activities and albumin levels were comparable in all groups. Total serum protein level was slightly decreased in females of the high dose group. Urinalysis was not affected. The relative weights of the caecum were distinctly increased at the high dose group in both sexes and at the mid dose group in females only. The weights of the liver and kidneys were slightly increased in females of the high dose group. Gross pathology did not show significant findings, except for enlargement of the caecum at the high dose group in both sexes but histopatholgy revealed no substance-induced findings.

 

Conclusion:

The No Observed Adverse Effects Level (NOAEL) for subchronic (90 days) oral toxicity in male and female Wistar rats was 30000 ppm (corresponding to about 1500 mg/kg bw/day) under the conditions of the study.